All window decorations are configurable, the basic
idea is to have as much user-interface policy as possible controlled through the Lisp language.
Despite this extensibility its policy is currently very minimal
compared to most window managers. Its aim is simply to manage windows
in the most flexible and attractive manner possible. As such it does
not implement desktop backgrounds, applications docks, or other things
that may be achieved through separate applications.
All high-level wm functions are implemented in Lisp for future
extensibility or redefinition. Currently this includes menus (using
GTK+), interactive window moving and resizing, virtual desktop,
iconification, focus/transient window policies, frame theme definitions
and much more.
Also, most received events are exported to the Lisp environment through
``key-bindings'' and hooks, similar to in Emacs. These events include
pointer behaviour and many internal X11 events (enter/leave,
focus-in/focus-out, map/unmap, etc..)